DACS App Note

Linking TDM and 8AFA cards under MB4.x and later (#43)

Purpose

The purpose of this application note is to provide the user with the details of how to successfully link the TDM and 8AFA (Waveform Synthesizer) cards.

Applicability

This information is applicable for systems shipped with linked TDM and 8AFA cards and running Model Builder (MB) version 4.x software.

General Information

In versions of Model Builder prior to MB4.04e, the TDM and 8AFA cards were linked via the global bus but their Codecs were not synchronized. This resulted in periodic bursts of noise due to timing differences between the 2 cards. Cards of the same type, TDM/TDM and 8AFA/8AFA, however, had both their global busses and Codecs synchronized and had no such noise problems. MB4.04e, in combination with newer firmware on the TDM cards, overcomes this timing issue between the TDM and 8AFA cards.

Model Builder 4.04e automatically attempts to synchronize the Codecs and global busses between different type DSP cards when the "master_dsp" and "slave_dsp" commands are added to the configuration file. No additional user action is required to correctly connect these cards for systems shipped after 01 May, 2000.

Legacy Systems Issue

For systems shipped prior to 01 May, 2000 with linked TDM and 8AFA cards AND running MB4.04e, you must turn the codec synching OFF or you will get tremendous amounts of noise and buzzing on the global channels. Previous versions of TDM firmware supported global channel linking but timing differences between the TDM and 8AFA prevented codec synchronization.

To turn off the codec synching put the following command in the configuration file:

  codec_synch=off

Link Indications

To see if your TDM Master and 8AFA slave(s) have synchronized both their Codecs and global channels go to the Main Model Page, select "Waveform DSPs" and then select the "Times" submenu. Observe the following messages, in yellow, to the right of the page. Use the Page Up/Page Down keys in order to move from page to page.

  Page 1 of 3
  	Master Ck Bus>DSP2
  	Slave Ck Bus>DSP1
	
  Page 2 of 3
  	TDM Master Ck Sync/3
	  	Slave Ck Sync/1

To observe if you are linked globally but do not have synchronized Codecs, again go to the "Waveform DSPs", "Times" menu and you will see the following indications:

  Page 1 of 3
  	Master Gl Bus>DSP2
  		Master Gl Bus>DSP1
		
  Page 2 of 3
  	TDM Master Gl
  		Slave Gl

Restrictions

In the case of mixed TDM and 8AFA cards the TDM must always be the Master and configured as DSP#1.

You cannot have 2 TDMs and a single 8AFA (3 cards total) and have DSP1 be the Master for the other 2 cards. In this case either the 2 TDM are linked and the 8AFA is by itself -or- TDM#2 is the Master for the 8AFA and TDM#1 is by itself.

Multiple slaves of mixed type cards are only supported in the case of a TDM Master and several (2) 8AFA slaves.